ref: 4dfc6c8fa70d3109591a1f51cf0d8a7849aeb4dd
dir: /libfaad/bits.h/
/*
** FAAD - Freeware Advanced Audio Decoder
** Copyright (C) 2002 M. Bakker
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** $Id: bits.h,v 1.16 2003/02/16 18:17:10 menno Exp $
**/
#ifndef __BITS_H__
#define __BITS_H__
#ifdef __cplusplus
extern "C" {
#endif
#include "analysis.h"
#ifdef ANALYSIS
#include <stdio.h>
#endif
#define BYTE_NUMBIT 8
#define bit2byte(a) ((a+7)/BYTE_NUMBIT)
typedef struct _bitfile
{
/* bit input */
uint32_t bufa;
uint32_t bufb;
uint32_t bits_left;
uint32_t buffer_size; /* size of the buffer in bytes */
uint32_t bytes_used;
uint8_t no_more_reading;
uint8_t error;
uint32_t *tail;
uint32_t *start;
void *buffer;
} bitfile;
#if defined (_WIN32) && !defined(_WIN32_WCE)
#define BSWAP(a) __asm mov eax,a __asm bswap eax __asm mov a, eax
#elif defined(LINUX) || defined(DJGPP)
#define BSWAP(a) __asm__ ( "bswapl %0\n" : "=r" (a) : "0" (a) )
#else
#define BSWAP(a) \
((a) = ( ((a)&0xff)<<24) | (((a)&0xff00)<<8) | (((a)>>8)&0xff00) | (((a)>>24)&0xff))
#endif
static uint32_t bitmask[] = {
0x0, 0x1, 0x3, 0x7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF, 0x1FF,
0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF,
0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF,
0x7FFFFF, 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF, 0x7FFFFFF,
0xFFFFFFF, 0x1FFFFFFF, 0x3FFFFFFF, 0x7FFFFFFF
};
void faad_initbits(bitfile *ld, void *buffer, uint32_t buffer_size);
void faad_endbits(bitfile *ld);
void faad_initbits_rev(bitfile *ld, void *buffer,
uint32_t bits_in_buffer);
uint8_t faad_byte_align(bitfile *ld);
uint32_t faad_get_processed_bits(bitfile *ld);
void faad_rewindbits(bitfile *ld);
uint8_t *faad_getbitbuffer(bitfile *ld, uint32_t bits
DEBUGDEC);
/* circumvent memory alignment errors on ARM */
static INLINE uint32_t getdword(void *mem)
{
#ifdef ARM
uint32_t tmp;
((uint8_t*)&tmp)[0] = ((uint8_t*)mem)[0];
((uint8_t*)&tmp)[1] = ((uint8_t*)mem)[1];
((uint8_t*)&tmp)[2] = ((uint8_t*)mem)[2];
((uint8_t*)&tmp)[3] = ((uint8_t*)mem)[3];
return tmp;
#else
return *(uint32_t*)mem;
#endif
}
static INLINE uint32_t faad_showbits(bitfile *ld, uint32_t bits)
{
if (bits <= ld->bits_left)
{
return (ld->bufa >> (ld->bits_left - bits)) & bitmask[bits];
} else {
bits -= ld->bits_left;
return ((ld->bufa & bitmask[ld->bits_left]) << bits) | (ld->bufb >> (32 - bits));
}
}
static INLINE void faad_flushbits(bitfile *ld, uint32_t bits)
{
if (bits < ld->bits_left)
{
ld->bits_left -= bits;
} else {
uint32_t tmp;
ld->bufa = ld->bufb;
tmp = getdword(ld->tail);
ld->tail++;
#ifndef ARCH_IS_BIG_ENDIAN
BSWAP(tmp);
#endif
ld->bufb = tmp;
ld->bits_left += (32 - bits);
ld->bytes_used += 4;
if (ld->bytes_used == ld->buffer_size)
ld->no_more_reading = 1;
if (ld->bytes_used > ld->buffer_size)
ld->error = 1;
}
}
/* return next n bits (right adjusted) */
static INLINE uint32_t faad_getbits(bitfile *ld, uint32_t n DEBUGDEC)
{
uint32_t ret;
if (ld->no_more_reading)
return 0;
if (n == 0)
return 0;
ret = faad_showbits(ld, n);
faad_flushbits(ld, n);
#ifdef ANALYSIS
if (print)
fprintf(stdout, "%4d %2d bits, val: %4d, variable: %d %s\n", dbg_count++, n, ret, var, dbg);
#endif
return ret;
}
static INLINE uint8_t faad_get1bit(bitfile *ld DEBUGDEC)
{
uint8_t r;
if (ld->bits_left == 0)
return (uint8_t)faad_getbits(ld, 1 DEBUGVAR(print,var,dbg));
ld->bits_left--;
r = (ld->bufa >> ld->bits_left) & 1;
return r;
}
/* reversed bitreading routines */
static INLINE uint32_t faad_showbits_rev(bitfile *ld, uint32_t bits)
{
uint8_t i;
uint32_t B = 0;
if (bits <= ld->bits_left)
{
for (i = 0; i < bits; i++)
{
if (ld->bufa & (1 << (i + (32 - ld->bits_left))))
B |= (1 << (bits - i - 1));
}
return B;
} else {
for (i = 0; i < ld->bits_left; i++)
{
if (ld->bufa & (1 << (i + (32 - ld->bits_left))))
B |= (1 << (bits - i - 1));
}
for (i = 0; i < bits - ld->bits_left; i++)
{
if (ld->bufb & (1 << (i + (32-ld->bits_left))))
B |= (1 << (bits - ld->bits_left - i - 1));
}
return B;
}
}
static INLINE void faad_flushbits_rev(bitfile *ld, uint32_t bits)
{
if (bits < ld->bits_left)
{
ld->bits_left -= bits;
} else {
uint32_t tmp;
ld->bufa = ld->bufb;
tmp = getdword(ld->start);
#ifndef ARCH_IS_BIG_ENDIAN
BSWAP(tmp);
#endif
ld->bufb = tmp;
ld->start--;
ld->bits_left += (32 - bits);
ld->bytes_used += 4;
if (ld->bytes_used == ld->buffer_size)
ld->no_more_reading = 1;
if (ld->bytes_used > ld->buffer_size)
ld->error = 1;
}
}
static INLINE uint32_t faad_getbits_rev(bitfile *ld, uint32_t n
DEBUGDEC)
{
uint32_t ret;
if (ld->no_more_reading)
return 0;
if (n == 0)
return 0;
ret = faad_showbits_rev(ld, n);
faad_flushbits_rev(ld, n);
#ifdef ANALYSIS
if (print)
fprintf(stdout, "%4d %2d bits, val: %4d, variable: %d %s\n", dbg_count++, n, ret, var, dbg);
#endif
return ret;
}
#ifdef __cplusplus
}
#endif
#endif